Introduction to the coursework for CI228

Transcription

1 Introduction to the coursework for CI228 It is very unlikely that you would be able to complete this coursework without attending lectures and tutorials and following the suggested completion deadlines. Part 1 To complete several small Java programs, to help refresh your programming skills. You should complete exercises 1.1 & 1.2 by the end of week 1 You should complete exercises 2.1, 2.2 & 2.3 by the end of week 4 at the latest. Part 2 To enhance/ improve parts of the CatShop system This is composed of 5 sections worth in total 80% of the marks for the coursewwork. 3.1 & 3.2 worth 10% each. (20% Total) 3.3,3.4 & 3.5 worth 20% each. (60% Total) Remember the tutorials are an integrated part of this assignment and provide guidance to the construction of the programs. M A Smith University of Brighton September 25, 2014 Page 1

2 Deadlines When Deadline for Mon Tue Wed Thu Fri Sat Sun Part 1 Week 4 by 2/11/ :30 CE Part 2 Week 11 11/01/ :30 CS Demonstration Week 12 Mon Jan 12 - Fri Jan In your tutorial slot (Fill in) CE Charon exercises (Worth 20%) CS Completed CatShop system, plus supporting documentation. (Worth 80%) T Your tutorial slot in week 12. Fill in your tutorial slot day as indicated by your course timetable. Remember the demonstration is an integral part of the assignment. M A Smith University of Brighton September 25, 2014 Page 2

3 Helping your fellow students Please do not share code solutions with your fellow students. This will not help them and in fact may well hinder their learning in this module. By all means help your fellow students, by helping them with compile time and logical errors with in their program. You will probably find that this gives you a greater understanding of programming. Plagiarism/ Collusion etc. Your submission will automatically be submitted to the turnitin plagiarism detection system. M A Smith University of Brighton September 25, 2014 Page 3

4 Part 1 - Introductory exercises Summary of BIO Static method call BIO.getInt() BIO.getDouble() BIO.getString() Description Read a line and return as an int the number that is contained within the line. If the number is malformed then return 0. Read a line and return as a double the number that is contained within the line. If the number is malformed then return 0.0. Read a line and return as an instance of a String the characters that are contained within the line. Leading and trailing white space (tab or space characters) will be removed. If during a read the end of input is detected a warning message will be printed and the program will terminate. M A Smith University of Brighton September 25, 2014 Page 4

5 1.1 Easy, Familiarisation with the Charon system and Eclipse Brief Construct an application in Java to: write the message Hello Brighton to the terminal window. Expected output Submitting to Charon Hello Brighton Remember to submit the whole application which must have the class name Main to the Charon system. Eclipse When trying this with Eclipse you will also need to create the class BIO M A Smith University of Brighton September 25, 2014 Page 5

6 1.2 Easy, Familiarisation with the Charon system and Eclipse Brief Construct an application in Java to: Read in an integer number (will always be between 1-25) and print the times table corresponding to this number. The class BIO is automatically included when you use BlueJ or submit a program to Charon. If you want to use this at home then you need to include the code for the class BIO (see programs on web site) in your program. Input data Commentary Input 8 Time table Expected output 1 * 8 = 8 2 * 8 = 16 3 * 8 = 24 4 * 8 = 32 5 * 8 = 40 6 * 8 = 48 7 * 8 = 56 8 * 8 = 64 9 * 8 = * 8 = * 8 = * 8 = 96 Submitting to Charon Hints Remember to submit the whole application which must have the class name Main to the Charon system. Remember any line printed that contains a # will not be considered as part of your answer. This is so that you can write out a meaningful prompt (containing a # character) for any data required and this line of text will be ignored in the comparison of your answer. Use printf to control the layout of the numbers in your answer. M A Smith University of Brighton September 25, 2014 Page 6

7 Rounding errors with doubles and floats. Using an instance of a double or float to represent a monetary amount is not always a good idea because of rounding errors For example, in Java the result of calculating does not equal exactly 3.6. However, if you only print the result to a few decimal places then the answer will look correct. class Main public static void main( String args[] ) double sum = ; double result = sum; System.out.printf( "%30.28f\n", sum ); System.out.printf( "%30.28f\n", 3.6 ); System.out.printf( "%30.28f\n", result ); A double has about 16 decimal digits of accuracy. Do look up floating point numbers. Hence Holding a monetary amount in a double is not always a good idea, as rounding errors will lead to discrepancies in the 'money' held. Accountants would not be pleased. M A Smith University of Brighton September 25, 2014 Page 7

8 In relationship to the class Account class Account private double thebalance = 0.00; //Balance of account private double theoverdraft = 0.00; //Overdraft allowed public double getbalance() return thebalance; public double withdraw( final double money ) assert money >= 0.00; if ( thebalance - money >= theoverdraft ) thebalance = thebalance - money; return money; else return 0.00; public void deposit( final double money ) assert money >= 0.00; thebalance = thebalance + money; public void setoverdraftlimit( final double money ) theoverdraft = money; public double getoverdraftlimit() return theoverdraft; and the interfaces Transfer & Interest interface Interest public boolean incredit(); public void creditcharge(); //Is account in credit //Add credit charge (Daily) interface Transfer public boolean transferfrom( Account from, double amount ); public boolean transferto( Account to, double amount ); M A Smith University of Brighton September 25, 2014 Page 8

9 2.1 Easy / Moderate - but carefully read the description Brief Construct the class AccountBetter1: The class AccountBetter1 inherits from the class Account and implements the interface Transfer. The interface Transfer is defined as: Submitting to Charon Important interface Transfer public boolean transferfrom(account from, double amount); public boolean transferto(account to, double amount); Then: mike.transferfrom( miri, ); would transfer from miri (An instance of an Account) to mike (An instance of the class AccountBetter1). and mike.transferto( miri, ); would transfer from mike (An instance of AccountBetter1) to miri (An instance of Account). The boolean result returned is true if the transfer succeeded otherwise false. You should also return false for invalid transactions, such as attempting to transfer a negative amount of money. Submit only the class AccountBetter1 to the Charon system. The Charon system will provide the implementation of the class Account and the interface specification for Transfer. There should be no print statements in the class AccountBetter1. Do not change the implementation of class Account Using a double to represent money in a real application dealing with money is not a good idea, as small rounding errors can accumulate to give inaccurate results. M A Smith University of Brighton September 25, 2014 Page 9

10 Assuming appropriate declarations had been made the application shown below when run: class Main public static void main( String args[] ) AccountBetter1 mike = new AccountBetter1(); AccountBetter1 cori = new AccountBetter1(); Account miri = new Account(); mike.deposit( ); cori.deposit( ); miri.deposit( ); //Transfer from miri's account to mike's account mike.transferfrom( miri, ); //Transfer from mike's account to cori's account mike.transferto( cori, ); System.out.printf( "Mike = %5.2f\n", mike.getbalance() ); System.out.printf( "Miri = %5.2f\n", miri.getbalance() ); System.out.printf( "Cori = %5.2f\n", cori.getbalance() ); Would print: Mike = Miri = Cori = Extension Question (Easy): Why does mike.transferto( cori, ); compile and run, as cori is an instance of AccountBetter1. M A Smith University of Brighton September 25, 2014 Page 10

11 How the checking works When you submit your class AccountBetter1, an additional class Main is added to test you class, as well as the class Account to form a complete application. This application is then run which prints out the results from performing various transactions with an instance of your class AccountBetter1. The output from running this application is then compared against the output from running the code with a 'correct' version of AccountBetter1. What to do if the check fails If the check fails you will see a lot of output, but by looking at this output you will be able to see where your class delivered an incorrect result. Look first at the differences, then find these in the output from running your class. Work out why the differences have occurred. Example of part of the output from running the test Executing java Main Using the declarations: AccountBeter1 ab = new AccountBetter1(); Account a = new Account(); Then sending messages to these objects - gives: ab.deposit( ) ab.getbalance() -> a.getbalance() -> 0.00 a.deposit( ) ab.getbalance() -> a.getbalance() -> ab.transferto( a, ) -> returns true ab.getbalance() -> a.getbalance() -> ab.transferto( a, ) -> returns true ab.getbalance() -> a.getbalance() -> Which shows the result from messages sent to instances of the class Account & AccountBetter1. M A Smith University of Brighton September 25, 2014 Page 11

12 2.2 Moderate - but carefully read the description Brief Construct the class AccountBetter2: The class AccountBetter2 inherits from the class AccountBetter1 (written for exercise 2.1) and implements the interface Interest. The interface Interest is defined as: interface Interest boolean incredit(); //Is account in credit void creditcharge(); //Add credit charge (Daily) The method incredit returns true if the account is in credit (thebalance >= 0.0 ) and false otherwise. The method creditcharge is responsible for implementing a charge for credit if the account is overdrawn. The method will be called at the end of each day to work out the charge for any overdraft. Overdrawn accounts are currently charged 10% interest on the amount the account is overdrawn. When this method is called any balance overdrawn is multiplied by and this amount is deducted from the account. Thus if this method is called every day it will equate to an annual interest rate of 10% on the negative balance. Special instructions Important Hints Submit only the class AccountBetter2 that you have written to the Charon system. Do not change the implementation of class Account or class AccountBetter1. Think, about the case when deducting interest from the account will not be possible as the overdraft limit check will prevent this. You will need to change the overdraft limit to allow this withdrawal (for the interest charged) to happen, but not any other 'normal' withdrawals after this to take place. M A Smith University of Brighton September 25, 2014 Page 12

13 2.3 Moderate - but read carefully the description Brief Construct the class AccountStudent: The class Account Student inherits from the class AccountBetter2 (Written for exercise 2.2) This class overrides the method creditcharge so that a student account is not charged interest if the overdraft is less than or equal to 5,000. When an account is overdrawn by more then 5,000 then interest is charged on a daily bases on the full overdrawn amount. Thus if the account is overdrawn by 5,000 on a single day no interest is charged. If however, the next day the account is overdrawn by more than 5, then interest for that day would be charged on the whole overdrawn amount. Overdrawn accounts are currently charged 10% interest on the amount the account is overdrawn. This is calculated by multiplying the overdrawn balance by each day. When interest is calculated (using this rate) on all the days of a year it will equate to an annual interest rate of 10%. Special instructions Important Hints Submit only the class Account Student that you have written to the Charon system. Do not change the implementation of class Account class AccountBetter1 or class AccountBetter2 Think about the Java concept of overriding. To benefit fully from this exercise write a comprehensive program to test your class AccountBetter2 M A Smith University of Brighton September 25, 2014 Page 13

14 Part 2 The CatShop Overview [80% of c/w marks] This part of the coursework is the completion/enhancement of a 3 tired system that implements a computer system for the CatShop. Remember, that you need to start this part of the coursework at the times indicated. Like all coursework involving programming if you leave it to the last minute you will probably encounter a problem (that though simple to solve) will delay you sufficiently to prevent you completing most of this coursework on time. M A Smith University of Brighton September 25, 2014 Page 14

15 Exercises 3.3, 3.4 (3.5?) depend on exercise 3.2 working. Apart from this dependency the order of completion is immaterial. # Components to complete/ Implement 3.1 Using inheritance create a new class to provide enhanced functionality to the 10% original class Basket. Start and finish in weeks Complete the methods in the class Order that have been deliberately left 10% unfinished. Start and finish in weeks Produce a unit test for the class Order. The unit test should test the progression 20% of several orders through the system, from creation to collection. Start in week Enhance the Display client by using graphical components. Start in week 6 20% Any other enhancement(s) to the system 3.5 that you wish to make. 20% Start in week 6-8 M A Smith University of Brighton September 25, 2014 Page 15

16 About the CatShop part of the coursework Though a large amount of code is provided, you do not need to understand the details of much of this code base. By using OO techniques, modifications to a program can usually be isolated to a single class or at worst a few classes. For example, exercise 3.1 requires the completion of a single class plus (Not the best solution) a change to 1 line in another class. Exercises 3.2 & 3.3 require completing a single existing class. Exercise 3.4 will require an understanding of the architectural pattern MVC together with modifications to the code in the classes that compose this pattern for the shop display. Exercise 3.5 is an opportunity for you to demonstrate your programming skills by extending/ enhancing the CatShop system. M A Smith University of Brighton September 25, 2014 Page 16

17 3.1 Easy/ Moderate Brief Construct the class BetterBasket The class BetterBasket inherits from the class Basket (Core class of the CatShop) and should provide a better experience for users who interact with the system by: 1. Merging repeated product items into a single request for multiple product items. 2. Sorting the ordered items into ascending order (on the product key) The code given to you includes a skeleton implementation of the class BetterBasket. You will need to modify this class. In addition you will need to create a new instance of BetterBasket rather than Basket. The easiest way of doing this is to change the method makebasket in the class CashierModel to return a new instance of a BetterBasket. However a better way of doing this is to use the Factory method pattern in Main to create a new (inherited) version of CashierModel which overrides makebasket with a new method that returns an instance of a BetterBasket. This will mean that the major class CashierModel has not had to be changed. In fact you could have another cashier client running that exhibits the old behaviour. Remember, you must not change the code that accesses an instance of Basket in the rest of the CatShop system. Using the factory method pattern will gain higher marks. M A Smith University of Brighton September 25, 2014 Page 17

18 Hints One approach is to override the method add with the new functionality to merge and sort the contents of the basket after each new product is added. Do remember that an object retains its type, even after assignment. Do remember that you can assign an instance of a subclass to an instance of its super class. Do remember that there is one place in the CatsShop were an instance of a BetterBasket will need to be created. Do remember that Basket is inherited from an ArrayList<Product>. So that in any inherited class you can use the methods in the class ArrayList. Do remember that there is the method Collections.sort. M A Smith University of Brighton September 25, 2014 Page 18

19 3.2 Easy/ Moderate Brief Complete the class Order The class Order maintains the state of the orders in the system. Waiting Orders that can not be processed (picked) yet as all the pickers are busy collecting products from the warehouse shelves for other orders. Each picker process each order individually. Being Picked Orders that are currently being picked from the warehouse shelves. In the current system there are two 'pickers' but this may change. ToBeCollected Orders that are currently waiting at the collection desk for a customer to collect. Once collected the order is 'discarded' from the system. Once you have completed this class order the whole system will function to allow orders to be progressed through the system. Hints It may help to role play what happens in an instance of the class Order as individual clients interact with it. M A Smith University of Brighton September 25, 2014 Page 19

20 3.3 Moderate / Difficult Brief Construct a unit test for the class Order that you have completed. The aim to provide a test that checks the progression of orders through the system. You should think about providing some useful methods to help you do this. In particular think about (not exhaustive): 1. How extensible are your tests. 2. Is the code easy to follow, concise, easy to modify. Could you factor out some parts into seperate methods that complete part of a test. 3. Does it check for error conditions such as orders becoming lost, not being progressed correctly etc. Hints Do think about what could go wrong in the code of the class Order. Do check what happens when there are several orders in the system. Do check that the returned values from the methods are correct. Do simplify the code by factoring 'common code' sequences into a single method call. Sometimes writing a Unit test can be more difficult than writing the class that it is testing. M A Smith University of Brighton September 25, 2014 Page 20

21 3.4 Moderate / Difficult Brief Use graphics to better display to customers the current state of the orders in the computer system. You should still use the MVC architectural pattern, but enhance the display to better show to customers the state of the system. Think about (not exhaustive): 1. What information, should be shown. Could it be shown graphically. 2. Would it be better to display orders in sorted order. This can happen if items are picked by several pickers. 3. What happens if the orders can not all be displayed at once on the screen. Incorporate your enhanced display into the CatShop system. Hints Do look at how the MVC architectural pattern works. Do think about what the display will look like. Do think about using animation to enhance the visual experience of the customers. M A Smith University of Brighton September 25, 2014 Page 21

22 3.5 Easy / Moderate / Difficult Brief Implement any other enhancement(s) to the system that you wish to make. This is to allow you to correct/ enhance / make more realistic the system. Some suggestions (not exhaustive): 1. Easy Record the orders that have been collected for later analysis to a file. 2. Easy / moderate / difficult Allow for the case when a picker finds that a product is not in the warehouse. 3. Moderate / difficult Add a remove button to remove the last order added to the shopping basket. Assume that in the future more than one item of a particular product may have been added to the shopping basket in separate actions. Thus you need to remember the transactions carried out on the shopping basket so that they can be undone individually. 4. Difficult Create a new display client that is on a remote device such as an android table/ phone. You will need to run the distributed version of the CatShop system for this extension. This is deliberately vague to allow you to use your imagination and programming skills to add to the functionality of the CatShop. High marks will be awarded for a significant extension(s) to the CatShop system. Just changing the colour of the display is not significant. M A Smith University of Brighton September 25, 2014 Page 22

23 What to submit (Complete project) A single zip file ci228_your_name.zip containing the following directory structure: In the top level directory: doc A single pdf file that contains the written part of your course work. (See below) In the top level directory: src The source files of your implementation of the game. In the same form as the original directory structure in the file jd3.zip or jd3.tgz. The toplevel file 00Readme.txt that explains how to compile and run your program In the top level directory: class The class files to run your program. You need to test this so that it can be run by simply typing at a cmd windows whose current directory is at the package level of the CatShop class files. java clients/setup java clients/main Alternatively provide a jar file for the applications with appropirate instructions to run java -jar Setup.jar java -jar Main.jar What to submit (Written part only) The pdf file to the turnitin system (More details later) M A Smith University of Brighton September 25, 2014 Page 23

24 Written part of your coursework index The class BetterBasket Listing (Your code highlighted) Critique of your code Testing/ Example of output For the class Order Listing (Your code highlighted) Critique of your code Testing/ Example of output Testing of the class Order using a JUnit test Listing (Your code highlighted) Critique of your unit test Testing/ Example of output Code for the Client Display Listing (Your code highlighted) Critique of your code Testing/ Example of output Your extension(s) / modification(s) Listing (Your code highlighted) Critique of your work Testing/ Example of output M A Smith University of Brighton September 25, 2014 Page 24

25 What is a listing of your code A neatly indented code listing, with appropriate comments neatly laid out so that another programmer could easily follow your code. The code listing should be in a non proportional font for example Courier. (Minimum size 9 point) You should also show any lines of code that you have changed in the rest of the application. For example, in completing the class BetterBasket you at some point would need to create an instance of BetterBasket that is used by the cashier client. Do remember, that a badly laid out program will have a negative impact on the marks awarded. For example, in Question 3.2 only show the methods that you have completed in the class Order, you do not need to show any method in this class Order that you have not changed. What is a critique of your code A description with critical comment on the implementation route taken. You should include reflection on any advantages / limitations to your code as well as the general approach that you have taken. What is testing/ Examples of output Test data you used, with expected results. Evidence of this for example (screen shots) of your program giving the expected results. Any Unit testing that you have done. M A Smith University of Brighton September 25, 2014 Page 25